Amorphous aluminum-based alloys

ABSTRACT

A substantially amorphous or microcrystalline Al-based alloy, wherein said Al-based alloy is represented by the formula: 
     
         Al.sub.a M.sub.b M&#39;.sub.c X.sub.d Y.sub.e 
    
     in which: 
     a+b+c+d+e=100 
     50≦a≦95 atom % 
     0≦b≦40 atom % 
     0≦c≦15 atom % 
     0≦d≦20 atom % 
     0≦e≦3 atom % 
     wherein at least two of the subscripts b, c or d are strictly positive, and wherein M is at least one metal selected from the group consisting of Mn, Ni, Cu, Zr, Cr, Ti, V, Fe and Co; M&#39; is Mo, W, or a mixture thereof, X is at least one element selected from the group consisting of Ca, Li, Mg, Ge, Si, and Zn; and Y is the inevitable production impurities, with the proviso that when element M is Co, Mn and/or Ni, the total amount of these elements is at least 12 wt % of the alloy.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.506,993 filed June 23, 1983, U.S. Pat. No. 4,595,429.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to substantially amorphous or microcrystallineAl-based alloys.

There are many alloys in an amorphous state, which are produced by rapidcooling at a rate which is generally higher than 10⁵ ° C./sec from arandom state (liquid or vapor). In particular, alloys of type T_(i)X_(j) are known, in which T represents one or more transition metals (inparticular iron) and X represents one or more metalloids(non-metalloids) such as B, P, Si, C, Al, with i≧50 atom %. In suchalloys, Al occurs as a minor element, the proportion of which, generallyof the order of 10 atom %, does not exceed 35 atom %.

For Al-based alloys (containing more than 50 atom % Al), the technicalliterature reports on attempts to produce amorphous alloys, which werecarried out in relation to binary alloys containing Bi, Cd, Cu, Ge, In,Mg, Ni, Pd, Si, Cr, Ag or Zn, but only four of them, Al-Ge, Al-Pd,Al-Ni, Al-Cr were found to be very locally amorphous (regions which arevisible in electron microscopy), and that occurs with very high rates ofcooling of the order of 10⁹ to 10¹⁰ K/sec, which are very difficult toattain on an industrial scale: see T. R. Anantharaman et al. "RapidlyQuenched Metals III", volume 1, Editor B. Cantor, The Metals Society,London (1978) page 126 and P. Furrer and Warlimont, Mat. Science andEng., 28 (1977) page 127.

With regard to ternary alloys, amorphous alloys were produced by A.Inoue et al., (Journal of Mat. Science 16, 1981, page 1895) but theyrelate to the systems (Fe, Co, Ni)-AL-B, which may contain up to 60 atom% Al and generally from 15 to 45-50 atom % B.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 shows the X-ray diagram of an alloy Al₈₀ Cu₁₀ Ni₈ Mo₂, which isproduced by means of monochromatic radiation of Co (λ=0.17889 nm);

FIG. 1a shows the diagram of the amorphous alloy, FIG. 1b being a partof the FIG. 1a diagram on an enlarged scale;

FIG. 1c shows the diffraction diagram of the corresponding crystallizedalloy; and

FIG. 2 shows the variation in hardness of the amorphous alloy accordingto the invention, versus time, when maintained at a temperature of 150°C.

SUMMARY OF THE INVENTION

The invention therefore concerns alloys based on Al, free from boron,which can be produced in a substantially amorphous or microcrystallinestate, by cooling at rates of the order of 10⁵ to 10⁶ K/sec, which canbe attained on an industrial scale, from a liquid or gaseous state.

The expression substantially amorphous alloy is used to denote a statein which the atoms are not in any order at a great distance,characterized by broad and diffuse X-ray diffraction spectra, withoutcharacteristic lines of the crystallized state; corresponding electronmicroscope investigations show that more than 80% by volume of the alloyis amorphous.

The expression microcrystalline state is used to denote an alloy inwhich 20% of the volume or more is in a crystallized state and in whichthe mean dimension of the crystallites is less than 1000 nm, preferablyless than 100 nm (1000 Å). Said mean dimension is evaluated from themid-height width of the line of the dense planes of the alloy, or byelectron microscopy (in the black field). In that state, the diffractionlines at low angles (θ<22°) have disappeared.

The microcrystalline alloys are generally produced either directly fromthe liquid state or by thermal crystallization treatment above theinitial crystallization temperature Tc of the amorphous alloy (that isdetermined hereinafter by differential enthalpic analysis, with aheating rate of 10° C./min). The alloys according to the invention havethe following chemical composition, defined by the formula:

    Al.sub.a M.sub.b M'.sub.c X.sub.d Y.sub.e

in which:

    50≦a≦95 atom %

M represents one or more metals of the group Mn, Ni, Cu, Zr, Ti, V, Cr,Fe, and Co with

    0≦b≦40 atom %

M' representing Mo and/or W with

    0≦c≦15 atom %

X represents one or more elements of the group Ca, Li, Mg, Ge, Si, Znwith

    0≦d≦20 atom %, and

Y represents the inevitable production impurities such as O, N, C, H,He, Ga, etc., the total proportion of which does not exceed 3 atom %, inparticular for the lightest elements, but which are preferably held at alevel below 1 atom %. The scope of the invention is further modified bythe limitation that when M is Co, Mn and/or Ni, the total amount ofthese elements in the alloy is at least 12 wt. %, and that the value ofat least two of the subscripts b, c and d are strictly positive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The proportion of additional elements is limited in an upward directionby virtue of metallurgical considerations (melting temperature,viscosity, surface tension, oxidizability, etc) but also inconsideration of economic factors (price and availability). The Mo and Ware limited to 15% as they substantially increase the density and themelting point of the alloy.

It has been found that it is easier to produce a substantially amorphousor microcrystalline alloy if the proportion of Al is limited in anupward direction to 85 atom %.

Substantially amorphous or microcrystalline alloys were produced withalloys containing between 6 and 25 atom % of Cu, with a value of 15≦b≦40atom %, with the level of impurities being held at less than 1 atom %.

Preferred compositions comprise individually or in combination, from 0.5to 5 atom % Mo, from 0.5 to 9 atom % Si, from 5 to 25 atom % V and 7 to25 atom % Ni.

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purpose of illustration only and are not intended to belimiting unless otherwise specified.

EXAMPLES Example 1

Various alloys were poured in a helium atmosphere at 30 kPa (0.3 bar)from a liquid bath in a quartz crucible, on to the outside of a mildsteel drum with a diameter of 25 cm, rotating at a speed of 3000 rpm(V≃40 m/sec), so as to produce a strip measuring 2 mm×20 μm incross-section.

The results of micro-hardness and/or X-ray study obtained thereon areset out in Table I below.

Example 2

The alloy Al₈₀ Cu₁₀ Ni₈ Mo₂ produced above, which has a crystallizationtemperature Tc=156° C. and a density of 3.7 g/cm³, and with a ratio inrespect of electrical resistance in the amorphous state, relative toresistance in the crystallized state, at 300° K., of 7, was held at atemperature of 150° C.; FIG. 2 shows the variation in Vickersmicro-hardness, under 10 g, in that test: it reaches about 500 HV, after10 hours.

Example 3

The alloy Al₇₂ Cu₁₅ V₁₀ Mo₁ Si₂ prepared as in Example 1 has acrystallization temperature of 360° C. and a density of 3.6 g/cm³. Itsmicro-hardness reaches 750 HV after being held at 400° C. for half anhour and 840 HV after being held at 450° C. for half an hour.

The very high levels of hardness are advantageous with regard toproducing powders with a very high level of chemical homogeneity, bycrushing.

The alloys according to the invention may be produced using knownmethods, in the form of wires, strips, bands, sheets or powders in theamorphous state and/or in the microcrystallized state. They may be usedeither directly or as means for reinforcing other materials or they mayalso be used for producing surface coatings for enhancing corrosion orwear resistance.

                  TABLE I                                                         ______________________________________                                                     POURING    VICKERS                                                            TEMPER-    MICRO-                                                             ATURE      HARDNESS    STATE                                     COMPOSITION  (°C.)                                                                             UNDER 10 g  x                                         ______________________________________                                        Al.sub.72 Cu.sub.15 V.sub.10 Mo.sub.1 Si.sub.2                                             1140       500         A                                         Al.sub.80 Cu.sub.9 Ni.sub.7 Mo.sub.1 Si.sub.3                                              850        400         A                                         Al.sub.75 Cu.sub.12 Ni.sub.10 Mo.sub.1 Si.sub.2                                            850        260         A                                         Al.sub.75 Cu.sub.11 Ni.sub.9 Mo.sub.2 Si.sub.3                                             850        220-410     A                                         Al.sub.70 Cu.sub.13 Ni.sub.11 Mo.sub.3 Si.sub.3                                            850        490         A                                         Al.sub.65 Cu.sub.16 Ni.sub.12 Mo.sub.3 Si.sub.4                                            850        410         A                                         Al.sub.80 Cu.sub.10 Ni.sub.8 Mo.sub.2                                                      850        310-360     A                                         Al.sub.60 Cu.sub.21 V.sub.14 Mo.sub.2 Si.sub.3                                             1300       --          A                                         Al.sub.77 Cu.sub.12 V.sub.8 Mo.sub.1 Si.sub.2                                              --         --          A                                         Al.sub.85 Cu.sub.8 V.sub.5 Mo.sub.1 Si.sub.1                                               --         --          A                                         Al.sub.80 Cu.sub.10 V.sub.7 Mo.sub.1 Si.sub.2                                              --         --          A                                         Al.sub.65 Cu.sub.18 V.sub.12 Mo.sub.2 Si.sub.3                                             --         --          m                                         Al.sub.72 Cu.sub. 10 V.sub.14.5 Mo.sub.1 Si.sub.2.5                                        --         --          m                                         Al.sub.69 Cu.sub.17 Fe.sub.10 Mo.sub.1 Si.sub.3                                            --         --          m                                         Al.sub.72 Cu.sub.16.5 Fe.sub.8 Mo.sub.1 Si.sub.2.5                                         --         --          m                                         Al.sub.75 Cu.sub.14 Fe.sub.7 Mo.sub.1 Si.sub.3                                             --         --          m                                         Al.sub.78 Cu.sub.12 Fe.sub.6 Mo.sub.1 Si.sub.3                                             --         --          m                                         Al.sub.77 Cu.sub.12 Zr.sub.8 Mo.sub.1 Si.sub.2                                             1250       400         A-m                                       Al.sub.77 Cu.sub.12 Ti.sub.8 Mo.sub.1 Si.sub.2                                             1100       420         A-m                                       Al.sub.81 Cu.sub.12 Ni.sub.7                                                               850        --          A-m                                       Al.sub.80 Cu.sub.10 Ni.sub.8 Mo.sub.0.5 Si.sub.1.5                                         850        280         A-m                                       Al.sub.80 Mn.sub.18 Mo.sub.2                                                               960        550         m                                         Al.sub.85 Cu.sub.12 Si.sub.5                                                               850        --          m                                         Al.sub.83 Cu.sub.8 Ni.sub.4 Si.sub.5                                                       850        --          m                                         Al.sub.77 Cu.sub.11 Ni.sub.6 Si.sub.6                                                      850        250         m                                         Al.sub.78 Cu.sub.12 Mo.sub.2 Si.sub.8                                                      850        320         m                                         Al.sub.80 Cu.sub.10 Mn.sub.8 Mo.sub.2                                                      930        --          m                                         Al.sub.85 Cu.sub.7 Ni.sub.5 Mo.sub.1 Si.sub.2                                              850        490         m                                         Al.sub.77 Cu.sub.12 Cr.sub.8 Mo.sub.1 Si.sub.2                                             850        540         m                                         Al.sub.77 Cu.sub.12 Mn.sub.8 Mo.sub.1 Si.sub.2                                             850        390         m                                         Al.sub.83 Cu.sub.17                                                                        800        --          m                                         Al.sub.75 Cu.sub.13 Ni.sub.10 Mo.sub.2                                                     930        --          m                                         Al.sub.97 Ni.sub.3                                                                         850        --          M                                         ______________________________________                                         xA: amorphous  m: microcrystalline  M = macrocrystalline                 

Having now fully described this invention, it will be apparent to one ofordinary skill in the art that many changes and modifications can bemade thereto without departing from the spirit or scope of the inventionas set forth herein.

What is claimed as new and is intended to be secured by Letters Patent is:
 1. A substantially amorphous Al-based alloy, wherein said Al-based alloy is represented by the formula:

    Al.sub.a M.sub.b M'.sub.c X.sub.d Y.sub.e

in which: a+b+c+d+e=100 50≦a≦95 atom % 0≦b≦40 atom % 0≦c≦15 atom % 0≦d≦20 atom % 0≦e≦3 atom %wherein at least two of the subscripts b, c or d are strictly positive, and wherein M is at least one metal selected from the group consisting of Mn, Ni, Cu, Zr, Cr, Ti, V, Fe and Co; M' is Mo, W, or a mixture thereof X is at least one element selected from the group consisting of Ca, Li, Mg, Ge, Si, and Zn; and Y is the inevitable production impurities, with the proviso that when element M is Co, Mn and/or Ni, the total amount of these elements is at least 12 wt % of the alloy.
 2. A substantially amorphous Al-based alloy, wherein the said Al-based alloy is represented by the formula:

    Al.sub.a M.sub.b M'.sub.c X.sub.d Y.sub.e

in which: a+b+c+d+e=100; 50≦a≦85 atom %; 0≦b≦40 atom %; 0≦c≦15 atom %; 0≦d≦20 atom %; 0≦e≦3 atom %wherein at least two of the subscripts b, c or d are strictly positive, and wherein M is at least one metal selected from the group consisting of Mn, Ni, Cu, Zr, Cr, Ti, V, Fe and Co; M' is Mo, W, or a mixture thereof; X is at least one element selected from the group consisting of Ca, Li, Mg, Ge, Si, and Zn; and Y is the inevitable production impurities, with the proviso that when element M is Co, Mn or Ni, the total amount of these elements is at least 12 weight % of the alloy. 